Nondestructive sensing techniques are being developed which utilize an electromagnetic wave containing at least a part of a frequency band ranging from 30 GHz to 100 THz. Hereinafter the electromagnetic wave in this range is simply referred to as a terahertz wave. Further, analysis apparatuses are being developed which utilize an electromagnetic wave containing at least a part of a frequency band ranging from 100 THz (wavelength: 3 μm) to 430 THz (wavelength: 0.7 μm). Hereinafter the electromagnetic wave in this range is simply referred to as an infrared ray.
Japanese Patent Application Laid-Open No. 2008-241340 discloses a sensing technique with a terahertz wave for spectrometric analysis of a human exhalation air. In this technique, a substance (e.g., ethanol) in the exhaled air is aspirated into a hollow fiber and is analyzed by transmission of a terahertz wave through the substance. The aspiration is conducted for increasing the concentration of the gaseous substance in the hollow fiber.
Japanese Patent Application Laid-Open No. 2005-147962 discloses an apparatus for measuring a concentration of a gaseous substance. This apparatus collects in a cell a gas evolved from a human arm skin, and detects a transmitted light beam after multiple reflection by mirrors equipped in the cell. This apparatus is equipped with a mechanism which adsorbs the gas evolved from the arm skin with an adsorbent and desorbs the gas from the adsorbent by heating to improve the detection sensitivity.